Updated documentation.

doc/api.rst

@@ -1,4 +1,34 @@
 Customizing RHEAS
 =================================
 
+Initializing and updating the database
+--------------------------------
+
+The RHEAS database needs to be populated with a variety of datasets that can be fetched automatically. A configuration file can be used to control and define which datasets are downloaded and imported in the PostGIS database. The configuration file follows the `INI <http://en.wikipedia.org/wiki/INI_file>`_ format, with each section corresponding to a dataset.
+
+Unless the entire spatial extent of the datasets needs to be ingested into the database, a ``domain`` section should be created in the configuration file describing the bounding box for the domain of interest.
+
+* ``minlat``: the minimum latitude of the bounding box
+* ``maxlat``: the maximum latitude of the bounding box
+* ``minlon``: the minimum longitude of the bounding box
+* ``maxlon``: the maximum longitude of the bounding box
+
+If the dataset is being fetched for the first time, a starting date needs to be provided within each dataset section while an ending date can be optionally provided.
+
+* ``startdate``: start date of data fetched (format is year-month-day)
+* ``enddate``: the last date of data to be fetched
+
+If the dataset already exists in the database, then RHEAS will only download data after the last date available in the database (unless this is bypassed by the ``startdate`` keyword).
+
+After the configuration file has been created, the database can be initialized/updated by calling RHEAS as
+
+.. highlight:: bash
+
+::
+
+./bin/rheas -u data.conf
+
+where ``data.conf`` is the name of the configuration file.
+
+